Effect of temperature variation on zebra fish health and behaviour Water temperature is an important environmental parameter that influences the distribution and the health of fishes. Moreover, temperature has a central role in ectothermic animals affecting their physiology and behaviour. The aim of this study was to determine the effects of ambient temperature on the molecular mechanism and the behavioural responses in ZF (Danio rerio) (ZF) a widely used animal model for environmental "omics" genomics researches. A global proteomic analysis was performed on fish brains to investigate physiological and biochemical changes that may occur from the exposure to this environmental stressor at the central nervous system level. Behavioural investigations were performed using a Y-Maze task to evaluate how temperature variations may affect swimming performance, the response to novelty and the spatial memory. Adult specimens of wild type ZF were kept at three different temperatures: 18 °C, 34 °C and 26 °C (used as a control) for 21 days. Proteomic data revealed 202XXX differentially expressed proteins across acclimation groups. These proteins are involved in energy metabolism, mitochondrial regulation and cytoskeletal organization. Temperature variation was able to alter swimming performance in adult ZF and to induce variations in the novel ambient exploration and in the acquisition and consolidation of spatial memory. This study indicates that moderate temperature variations can elicit biochemical changes that may affect fish health and behaviour. This combined approach may provide insights into mechanisms supporting thermal adaptation and plasticity in fishes.